Plating rack



J. N; KELLY PLATING RACK Filed May 26, 1932 9 gm 97. 7! 2 @62 Aalzw'Patented Aug. 14, 1934 PLATING RACK John N. Kelly,

Cleveland, Ohio Application May 26, 1932, Serial No. 613,682

2 Claims.

This invention relates to a method of and apparatus for platingarticles, and more particularly to a method and apparatus foreconomically plating certain portions of small articles, for example theheads of bolts.

In ordinary plating methods, the same thickness of metal is depositedupon substantially all of the unprotected surface of the article to beplated. For example, in the nickel plating of bolt heads it has beenfound that by the time a thousandth of aninch of plating is deposited onthe head of a bolt, the same thickness of plating has been built up onthe top of the threads. The plating action takes place unevenly on Vthreads, and distorts them to such an extent that when a thousandth ofan inch has been deposited on the bolt heads, the threads would nolonger fit the gauge specified for the particular bolts. Also, platingthe entire bolt in order to obtain a coating on the head results in anexpensive waste of power and material.

Accordingly, a general object of my invention is -to provide aneconomical method and apparatus for plating desired portions of smallarticles. A specific object of my invention is to provide aninexpensive, efficient method and apparatus for plating the heads ofbolts without depositing an objectionable amount of plate on the threadsof the bolts.

My prior application, Serial No. 532,110, filed April 22nd, 1931, showsan efficient plating rack which is well adapted for plating smallarticles, such as bolts, on a production basis. The apparatus comprisinga part of the present invention is an improvement on the plating rackshown in my copending application in that means are provided to shieldthe threaded portions of the bolts from the plating action, so that onlythe heads thereof will receive a deposit of material thickness.

In the drawing, Fig. 1 is a section through a plating bath showing myapparatus positioned therein, with a portion of the apparatus brokenaway; Fig. 2 is an elevation of the apparatus removed from the bath;Fig. 3 is a section along the line 33 of Fig.2; Fig. 4 is a sectionaldetail taken along the line 44 of Fig. 2, and Fig. 5 is a crosssectionaldetail on an enlarged scale taken along the line 5-5 of Fig. 2.

I have shown my invention in connection with the plating of bolts, butit is to be understood that my method and apparatus may be adapted foruse in connection with the plating of any small articles on a productionbasis, particularly when it is desired to plate certain portions of thearticle and leave the remaining portions without any substantial depositof plate.

A preferred arrangement of my invention includes a holder 10, which isadapted to be suspended within a plating bath 11, and which is providedwith means for enabling the articles to be quickly engaged and released,and for shielding the portions of the articles which are not to beplated from the plating action.

The holding mechanism is quite similar to that illustrated in mycopending application, Serial No.-532,010, and a preferable arrangementmay comprise current-carrying bars 12, that are provided withspacedopenings 13, into which the bolts 15 or other articles to beplated may be inserted. In the drawing, bolts are shown in only a few ofthe openings 13, but it is to be understood that in ordinary practice abolt will be placed in each of the openings in the rack. The members 12may be held in the form of a frame by cross-bars 16 secured to therespective members at spaced intervals, sufiicient cross-bars beingemployed to give the rack the required strength and rigidity.

To hold the bolts or other members in place,

I may employ a clamp which is adapted to clamp or release all the boltssimultaneously. Such a clamp may comprise a plurality of yieldable wires'20, which are attached rigidly to a bar 21 which is in turn mounted forlongitudinal movement on the cross-member 16, as by pin and slotconnections 22. The longitudinal bar may be actuated by a lever 23 whichmay be pivotally mounted on a bracket 24, and which may be held inclamping position by a keeper 25.

As shown clearly in Fig. 5, the resilient wires preferably engage thebolts immediately below the heads thereof and lie between the bolt headsand the conducting bars 12. The openings 13 are slightly larger than theshank of the bolts, so that the bolts may be readily inserted therein.When the bolts areclamped in place, they will be tilted slightly, thusmaking contact on opposite sides of the openings, as at 27 and 28.

In order to prevent the rack from being plated during use, the entirerack is preferably provided with an insulating coating, of rubber orother material, as indicated at 26. After' the coating has been applied,the holes 13 are reamed out to prcvidea contacting surface forconducting electricity to the bolts.

' It is well known that the rate at which metal is deposited inelectro-plating operations, is largely dependent on the current densityemployed. I have found that by shielding the electrolyte which is incontact with, for example, the threads h of the bolts, while allowingthe heads to remain in the main body of electrolyte, it is possible tolocally reduce the current density to such an extent that the requiredthickness of metal may be 5 deposited on the heads without depositing amaterial amount on the threaded portion. By this means, any distortionof the thread is prevented, and as only a comparatively small area ofthe bolt is plated, the power required is much less and the amount ofplating material used is greatly reduced.

In order to shield the threaded portions of the bolts from the platingaction, I have provided hollow shielding members 30, which may be madeof any suitable insulating material, such as hard rubber, and as shownin Fig. 4, may have a substantially semi-cylindrical cross-section.Bolts 31 fasten the shields to the bars 12 and press them against theinsulating material 26 with sufficient firmness to provide substantiallyfluid-tight joints between the bars and the shields. In order tofacilitate rinsing of the shields, small openings as at 32 may be formedin the bottom thereof. The shields therefore comprise backing stripswhich cooperate with the openings 13 to provide pockets for receivingthe bolts or other articles to be plated.

As indicated in Fig. 1, the shields extend abovethe level of theelectrolyte, so that the only means by which the'electrolyte within theshields can communicate with the main body of electrolyte in the platingbath is through the restricted path around each bolt and through thesmall slots 32. The total cross-sectional area of such paths is quitesmall, and therefore there will be considerable resistance to thepassage of current from the main body of electrolyte to the portionwithin the shields. Thus, the current density on the shanks and threadedportions of the bolts will be much less than the current density on theheads of the bolts which are exposed to the main body of the electrolyteand as a result of this difference a layer of metal of the requiredthickness may be deposited on the heads before any substantial depositwill be made on the threaded portions of the bolts.

It will be seen that I have provided a convenient method and apparatusfor plating certain desired portions of small articles; that my methodmay be carried out with a minimum amount of trouble; that it will resultin substantial savings in power and material cost and will prevent anyundesired and troublesome deposits of plating material.

I claim:

1. In a device of the character described, the combination with a holderhaving spaced article receiving pockets therein adapted to shield oneend portion of the article from the plating current, and a flexibleclamp carried by the holder and movable with relation thereto, saidclamp when moved in one direction being adapted to engage all of thearticles substantially simultaneously and to hold them in currentconducting contact with the holder, and when moved in the oppositedirection being adapted to release all of the articles substantiallysimultaneously whereby they may drop by gravity from the holder.

2. In a device of the character described, the combination with arelatively stationary bar having spaced article receiving openingstherein, a hollow shield carried by the bar on one side thereof forshielding one end portion of the articles from the plating current, aclamp movably mounted on the bar on the side opposite the shield andhaving yieldable portions thereon for engaging each of the articles,Whenever the clamp is moved in one direction, so as to lock all of themsubstantially simultaneously in current conducting contact with the bar,and to release all of them substantially simultaneously, whereby theymay drop by gravity from the bar whenever the clamp is moved in theopposite direction with reference to the bar, said bar having a hookadjacent the top thereof for suspending it in a plating bath.

JOHN N. KELLY.

